Picture of the Week

30 March 2020: This Picture of the Week captures the Milky Way streaking across the skies above the Chilean Atacama Desert. Dark wisps of interstellar dust form a turbulent mix with the bright glow of hot gas and billions of stars, creating a scene reminiscent of the thick smoke trail of a rocket after launch. In contrast to the tempestuous sight above, a tower at ESO’s Paranal Observatory stands serenely beneath the evening sky. Paranal is home to the Very Large Telescope (VLT), a ground-breaking observatory composed of four Unit Telescopes and four movable Auxiliary Telescopes. The telescopes can be used in different combinations to form an interferometer, combining the light they collect and allowing astronomers to study the Universe in spectacular resolution. The VLT has achieved many scientific firsts over the years, including tracking individual stars orbiting the centre of the Milky Way at unprecedented speeds. This indicated the presence of a ...

23 March 2020: The entire Universe is constantly on the move, from individual atoms all the way up to massive galaxy clusters. This is beautifully showcased in an image such as this, taken from the Chajnantor plateau some 5000 metres up in the Chilean Atacama Desert. This extremely arid and remote environment is home to the Atacama Large Millimeter/submillimeter Array (ALMA), the largest telescope array in existence. The blurred object is a specialised transporter, caught in the act of carefully carrying one of ALMA’s 66 high-precision antennas to a specific position on the plateau. By arranging the antennas in more extended configurations, astronomers can obtain far more highly spatially resolved images (meaning that the image is more detailed), while more compact configurations give better sensitivity for sources which spread over more of the sky. There’s movement going on above, too. Smooth stretches of cloud sweep across the pristine Chilean sky under the ...

16 March 2020: This picture of the week showcases the night sky over the construction site for the Extremely Large Telescope. A beautiful array of stars and the hazy band of the Milky Way are clearly visible above the site. In order to see the Milky Way so distinctly, one must be in an area with low light pollution, such as the Chilean mountain Cerro Armazones, when there is little or no moonlight. The ELT will be “the world’s biggest eye on the sky” when it begins operating. With a 39-metre primary mirror, the ELT will search the sky in the optical and near-infrared wavelength regions for new exoplanets, specifically Earth-like planets in orbit around other stars. The ELT will also be able to perform a kind of “stellar archaeology,” answering fundamental questions about how planets, primordial stars, primordial galaxies and black holes form and evolve. Perhaps the most exciting goal of the ...

9 March 2020: This beautiful image shows the dense heart of the Milky Way stretched out above one of the Auxiliary Telescopes of ESO's Very Large Telescope (VLT). Such dark and star-studded skies are typical of the VLT’s location in the Chilean Atacama Desert, which offers spectacular views such as this night after night for all of the site’s astronomers, visitors, and staff to enjoy. The VLT is made up of four large Unit Telescopes, and four smaller and movable Auxiliary Telescopes (one of which is shown here). These eight telescopes observe the cosmos both individually and as a team from various orientations and positions, allowing astronomers to study all manner of cosmic objects and phenomena in greater detail than ever before. The array has stimulated a new age of discoveries, with several notable scientific firsts — including the first image of a planet orbiting another star (known as an ...

2 March 2020: The soft glow of the Milky Way pours down like a waterfall over the VLT Survey Telescope (VST) at ESO’s Paranal Observatory. 2635 metres above sea level, the VST has an unparallelled view of the magnificently clear skies above Chile’s Atacama Desert. It is the largest telescope in the world dedicated to observational surveys in visible light, and it contributes to a vast range of studies, from discovering remote Solar System bodies to searching for exoplanet transits, to studying the structure and evolution of our galaxy. Above the VST, a few stars are particularly prominent just outside the main band of the galaxy: the bright reddish star is Betelgeuse, a red supergiant 640 light-years away thought to be on the brink of a supernova explosion. Betelgeuse and Bellatrix, the fainter white star to its left, are the shoulders of Orion the Hunter, one of the most famous and easily recognisable ...

24 February 2020: A new study led by Pierre Vernazza (Laboratoire d’Astrophysique de Marseille, France) conducted using ESO facilities has observed the asteroid Pallas for the first time at extremely high angular resolution. The asteroid could be successfully observed in such great detail thanks to the Adaptive-Optics (AO)-fed SPHERE imager on the Very Large Telescope (VLT). German astronomer Heinrich Wilhelm Matthäus Olbers first discovered Pallas on 28 March 1802. Named for the Greek goddess Pallas Athene, the asteroid — along with many other asteroids discovered in the 19th century — was initially classified as a planet. As time passed and technology improved, Pallas was later reclassified as an asteroid. Today it is famous for being the third-largest asteroid in the Solar System, with an average diameter of 512 km. Although Pallas is the largest known asteroid in the Solar System after Ceres and Vesta, it is the only one of these large asteroids ...

17 February 2020: Located deep in the Chilean Atacama Desert, far from the light pollution associated with human activity, is ESO’s Paranal Observatory: a world-leading research site that enjoys some of the darkest skies on Earth. Paradoxically, it is this extreme darkness that allows the sky to light up in technicolour in this image. The striking radiant light visible in the sky here is a phenomenon called airglow, which lends a magical appearance to the already breathtaking night sky. As the name suggests, airglow is a faint glow in the air created as atoms and molecules in the atmosphere combine and emit radiation. It is only visible in regions where the sky is dark enough that artificial lights do not overwhelm it. This phenomenon was the subject of ESOcast 78. This perspective was captured from the site of VISTA, the Visible and Infrared Survey Telescope for Astronomy. The trail of ...

10 February 2020: Stars are surrounded by something known as a corona — a diffuse aura of plasma that appears to surround them in the sky. For the Sun, we can best see this corona during a solar eclipse, when the Moon passes in front of the Sun and covers our star’s face. The solar corona then appears as a bright ring surrounding the eclipsed Sun. An image of the Sun’s corona as seen during a 1999 eclipse can be seen here. However, there is also the optical phenomenon of a corona, caused by the diffraction of light from a bright object — such as the Sun, other stars, the Moon, and bright planets — by water drops or ice crystals in the Earth’s atmosphere. This is occurring in this unusual image, where a rare corona of the planet Jupiter can be seen above the Atacama Desert in Chile. The beautiful red ...

3 February 2020: This remarkable photo shows the ESO La Silla observatory in the foreground with the planets Venus and Jupiter low in the sky and the Milky Way drifting behind them. Yet it took Zdenek Bardon, the photographer, three nights to capture this stunning image; astrophotographers are subject to the whims of the weather and this photo was no exception. He had to wait three days for a crystal clear night with no clouds and low humidity to capture Venus, Jupiter and the Milky Way in all their glory. La Silla is an exceptional location for astronomy because it has relatively low light pollution which allows the stars to appear crystal clear — although lights from human dwellings are visible on the horizon in this image. The site also offers exceptionally low humidity thanks to its elevation of 2400 metres above sea level. High humidity is a problem for both professional astronomers ...

27 January 2020: In this photograph, taken by ESO Photo Ambassador Babak Tafreshi, a slice of fiery colour streaks along the horizon near Paranal Observatory in northern Chile, bathing the four Unit Telescopes of the Very Large Telescope (VLT) in a soft, peachy glow. The Milky Way appears to soar directly up from one of the Unit Telescopes, bounded on either side by a spectacular array of stars — including Sirius, which dazzles at the top of the image. Part of Canis Major (The Greater Dog), Sirius is the brightest star in the sky and is actually a binary system, consisting of a main-sequence star (Sirius A, a star in stable “adulthood” that is burning nuclear fuel) and a white dwarf (Sirius B, the dense corpse of a star that ran out of fuel long ago). Wander down the edge of the Milky Way, and you might spy a small group of bright ...

20 January 2020: The Milky Way contains many regions of starbirth — areas where new stars are springing to life within collapsing clumps of gas and dust. One such region, named Gum 26, is shown here as imaged by the FORS instrument on ESO’s Very Large Telescope in Chile. Gum 26 is located roughly 20,000 light-years away in the southern constellation of Vela (The Sails). It is something known as an HII region or emission nebula, where the intense ultraviolet radiation streaming from newly-formed stars ionises the surrounding hydrogen gas, causing it to emit a faint pinkish glow. By catching new stars “pink-handed” in this manner, astronomers can learn more about the conditions under which stars arise, and study how they influence their cosmic environment. This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, ...

13 January 2020: Once used as the otherworldly lair for a James Bond villain, the ESO Residencia usually serves a far less sinister purpose! Since construction was completed in 2002, it has been a home from home for the astronomers, engineers and technicians working at ESO’s Paranal Observatory in Chile. The sleek building sits 2400 metres above sea level in the Mars-like Atacama Desert, just a few kilometres from Cerro Paranal — the mountain that hosts ESO’s Very Large Telescope (VLT) and Visible and Infrared Survey Telescope for Astronomy (VISTA). During the day the hotel is bathed in natural sunlight, which enters the building via a huge 35-metre-diameter dome on the roof. Seen here at night, the glass of the dome is beautifully illuminated beneath the Milky Way’s kaleidoscopic arch of blues, reds and pinks. Two neighbouring galaxies — the Large and Small Magellanic Clouds — can be seen as white smudges beneath ...

6 January 2020: Compared to their more intricate spiral cousins, elliptical galaxies resemble soft, hazy clouds. These galaxies have smooth, undefined boundaries, and bright cores surrounded by a fuzzy, diffuse glow. However, looks can be deceiving. At least 10% of ellipticals extend much further out into the cosmos than you might expect, and possess a range of far finer structures than first meets the eye — features such as loops and shells. Located around 100 million light-years away in the constellation of Pisces (The Fish), the galaxy to the upper-left of this image is named NGC 474. It is a stunning example of a shell elliptical galaxy; enormous wispy tails flick around the galaxy’s main body, while the inner structure is formed of a series of nested concentric rings. In fact, the full extent of the galaxy cannot even be contained in this field of view. The tendril-like outer regions of NGC 474 ...

30 December 2019: This Picture of the Week captures the skies above ESO’s Paranal Observatory ablaze with colour — blues, purples, oranges, greens, yellows and reds all mingle together to create this striking view of the Chilean site. One of the Auxiliary Telescopes (ATs) comprising ESO’s Very Large Telescope (VLT) is visible in the foreground, bathed in an eerie yellow-green glow. This AT is just one of the VLT’s four 1.8-metre auxiliaries, which also includes four giant 8.2-metre cousins (Unit Telescopes).The ATs are unique; they are self-contained and, depending on the needs of the observing project, can be repositioned in up to 30 different observing locations along a system of tracks. Acting together as the VLT Interferometer (VLTI), they capture light from celestial objects and send it to the same focal point through a system of mirrors housed within underground tunnels, allowing researchers to observe the cosmos in incredible detail. Comprising eight telescopes ...

23 December 2019: As the year draws to a close, we pause to extend a festive greeting to our community on behalf of everyone here at the European Southern Observatory. We wish you a very merry end of the year and a fruitful 2020! We look forward to sharing it with you all.

16 December 2019: Difficult as it may be, given the view above, when at Paranal Observatory make sure you keep your eyes on the ground — or you might just take a tumble. This Picture of the Week shows an entrance to one of the laboratories beneath the ESO’s Very Large Telescope (VLT) platform, used to carry out an astronomical technique known as interferometry. The VLT is composed of four large Unit Telescopes and four smaller Auxiliary Telescopes (ATs) — two of the latter are imaged here. Astronomers can use various combinations of these telescopes to pool their observing power and, using the technique of interferometry, achieve imaging resolutions much greater than is possible by any of them alone. This clever trick is performed beneath the platform in a network of tunnels filled with specialised equipment to direct and process the light gathered by the telescopes. Paranal Observatory is located in northern Chile ...

9 December 2019: This cloud-strewn new image of RCW 36 (or Gum 20) was captured by ESO’s Focal Reducer and low dispersion Spectrograph (FORS). It shows one of the sites of massive-star formation closest to our Solar System, about 2300 light-years away. Located in the constellation of Vela (The Sails), the RCW 36 emission nebula is only part of an even larger star formation complex, known as the Vela Molecular Ridge. Some areas in the clouds of RCW 36 are dense enough to block out background light, creating patches and wisps of inky black. Despite the dark appearance of these clouds, they are the only places in the Universe in which star formation occurs; clumps of molecular hydrogen and cosmic dust collapse and come together to form stars encircled by small families of planets, as in our own Solar System. FORS is mounted on ESO’s Very Large Telescope, one of the world's most ...

2 December 2019: Seen here, the majestic Milky Way rises above ESO’s La Silla Observatory in Chile, its bright band punctuated by red regions of star formation and dark, weaving filaments of interstellar dust. Two of the site’s telescopes, the 1-metre Schmidt telescope (left) and the MPG-ESO 2.2-metre telescope (right), are are visible as well. While all of the stars in the sky belong to the Milky Way galaxy, we commonly refer to this thick streak across the sky as “the Milky Way”. This is because of our position within our home galaxy: the Solar System sits on one of our galaxy’s spiral arms and is located roughly two-thirds of the distance between the Milky Way’s centre and its peripheries. The galaxy itself is shaped a little like a giant pancake with a bright bulge in the centre, with almost all of its constituent stars, gas, dust, planets, and so on lying within ...

25 November 2019: High up in the outskirts of the Chilean Atacama Desert, in the skies above ESO’s La Silla Observatory, a meteor blazes across the star-studded and dust-streaked Milky Way. This picturesque event had a silent, static onlooker, visible here to the left of the frame: the Swedish-ESO Submillimetre Telescope (SEST). The SEST was built in 1987 on behalf of ESO and the Swedish Natural Science Research Council, and was decommissioned in 2003.For those 16 years it gazed up at some of the darkest and clearest skies in the world. At the time of construction, the 15-metre SEST was the only large telescope in the southern hemisphere designed for submillimetre astronomy. While active, the SEST was used for a broad range of research, including observing the centre of the Milky Way, and studying our galaxy’s two satellites, the Magellanic Clouds. In 1995, SEST observations showed the Boomerang Nebula — ...

18 November 2019: ESO’s astronomical facilities in Chile are hives of activity — or oases! — in the otherwise barren and arid landscape of the Atacama Desert. This hostile and hard-to-reach location may seem like an odd choice for construction, but the Atacama is one of the best sites in the world for astronomy. It has practically no cloud cover, a distinct lack of light pollution, and is the driest non-polar location in the world, receiving under two centimetres of rainfall every year! Chile has hosted ESO’s telescopes since the 1960s, in observatories based at La Silla, Paranal, and Chajnantor Plateau. Shown here is the Visible and Infrared Survey Telescope for Astronomy (VISTA), situated at the Paranal Observatory. Perched atop a mountain adjacent to Cerro Paranal, the home of the flagship Very Large Telescope (VLT), VISTA is the largest telescope in the world designed to survey the sky in near-infrared light (just beyond ...